I have one ELL student in my class, and they are beginning to experience teasing because of their accent. They will sometimes stumble over words or mispronounce them, and while I choose to just ignore the mishaps, some of their classmates with laugh or mock the way they spoke. The ELL student doesn't seem to mind, so I don't want to blow it out of proportion and cause an issue if there really isn't one. How do I address this with my class and my ELL student?